Description
The A1242 Hall effect latch is a two-wire latch especially
suited for operation over extended temperature ranges, from
40 to +150癈. Superior high-temperature performance is
made possible through the Allegro
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patented dynamic offset
cancellation technique, which reduces the residual offset
voltage normally caused by device overmolding, temperature
dependencies, and thermal stress.
The current-switching output technique allows for the reduction
in cost in the wiring harness because only two connections to
the device are required. The current-switching output structure
also inherently provides more immunity against EMC/ESD
transients. These devices have low magnetic thresholds, thereby
enabling more flexibility in the magnetic circuit design.
The Hall effect latch will be in the high output current state
in the presence of a magnetic South Pole field of sufficient
magnitude and will remain in this state until a sufficient North
Pole field is present.
The A1242 includes the following on a single silicon chip:
a voltage regulator, Hall-voltage generator, small-signal
amplifier, chopper stabilization, Schmitt trigger, and a current
source output. Advanced BiCMOS wafer fabrication processing
takes advantage of low-voltage requirements, component
1242-DS, Rev. 6
Features and Benefits
?Chopper stabilization
?Superior temperature stability
?Extremely low switchpoint drift
?Insensitive to physical stress
?Reverse battery protection
?Solid-state reliability
?Small size
?Robust EMC capability
?High ESD ratings (HBM)
Two-Wire Chopper-Stabilized Hall Effect Latch
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Functional Block Diagram
Not to scale
A1242
Packages: 3 pin SOT23W (suffix LH), and
3 pin SIP (suffix UA)
Not to scale
Amp
Regulator
Low-Pass
Filter
GND
VCC
GND
Package UA Only
Clock/Logic
To All Subcircuits